An electronic oscillator is a device that allows for the generation of electronic signals at varying frequencies. One significant problem with oscillators is that, when coupled with a low supply voltage, the timing of the digital elements in the oscillator circuit becomes unreliable. Previous attempts to correct the timing of these elements have focused on the design of oscillator circuits which use latches, flip flops or monostable circuits, a two state circuit where one of the states remains stable but the other state is unstable for a fixed period of time before returning to a stable state (also known as “one-shot” circuits), to discharge the capacitors in the integrated circuits of the oscillators. The use of latches, flip flops or monostable circuits may operate sufficiently at standard operating supply voltage ranges, but are not reliable to control the charge and discharge of the oscillator capacitors for wide supply ranges. At low supply voltages, the oscillator may “lock up”, where one of the capacitors in the integrated circuit is continually charged, and the circuit does not switch over to charge the other capacitor.
At low supply voltages, the use of monostable circuits or other latches to control the charging and discharging of the capacitors in the oscillator circuit may be problematic. Monostable circuits are used to create specific time periods where one of the states of the circuit is unstable, and at low supply voltages, a determination of the timing becomes unpredictable. The use of monostable circuits in oscillators may therefore become unreliable. In oscillator configurations that use flip flops, the flip flops may startup in an invalid state and remain in this locked state during operation of the oscillator.
Other attempts to correct the timing of the integrated circuit elements of an oscillator at low supply voltages have centered on the use of multiple reference voltages. The use of two reference voltages presents multiple problems because it requires the use of two separate and distinct references that have a large voltage range, but still operate in the common mode range of the comparators in the oscillator circuit. The selection of two reference voltages to accomplish this is neither practical nor feasible at low supply voltages.
Thus there is a need in the art, particularly for oscillators on silicon chips that have a large voltage supply range, for an oscillator that may perform at low supply voltages without locking up.